The present invention relates to a motor vehicle headlight.
Known motor vehicle headlights generally comprise a paraboloid reflector closed at the front by a protective transparent shield and provided, at the rear, with a through hole usually coaxial with the optical axis of the headlight. Through the said hole, there is usually fitted and secured a lampholder extending inside the reflector and supporting, on its front end, a lamp having filaments located on the local point of the reflector itself.
For obtaining a light beam of given width and direction from the said headlight, known headlights are known to intercept both the direct light rays emitted from the front of the lamp, and the so-called parasitic light rays emitted from the rear of the lamp, away from the focal point of the reflector, that is, between the focal point and the rear of the reflector.
The direct rays emitted from the front of the lamp are usually intercepted by providing, inside the reflector, a dimming hood located in front of the lamp and along the optical axis of the reflector, or by simply coating the front of the lamp with paint impervious to light.
Intercepting the said parasitic light tays is generally more problematic, in that they bounce off the reflector to define parasitic beams usually diverging upwards and downwards in relation to the main beam produced by the light rays emitted by the lamp on the focal point of the reflector and reflected by the latter.
Of the aforementioned two parasitic beams, the upward-diverging one, which may dazzle oncoming vehicles, is usually intercepted by means of a secondary dimming hood fitted onto the reflector, over the central dimming hood. Alternatively, the lamp is provided with two tabs extending upwards and downwards from the front end of the lamp base and designed to intercept the parasitic rays in such a manner as to prevent their reaching the surface of the reflector.
It should be pointed out, in this connection, that not all currently enforced standards governing the brilliancy of headlights require the use of lamps having reflecting tabs, whereas secondary dimming hoods generally prove unsightly and relatively expensive.